Preliminary results on CERN GTK read-out chip prototype tests

1. Preliminary results on CERN GTK read-out chip prototype tests Massimiliano Fiorini CERN Gigatracker Working Group Meeting 8 December 2009

2. Measurement setup (1) Discriminated pixel output M. Noy (19/11/2009)

3. Measurement setup (2) • measurements by M. Noy and E. Martin • single PC controlling everything via USB and Ethernet • inject charge through pulses with fixed rise time (2.5 ns) and variable amplitude • Tektronics AFG3252 pulse generator driving charge injection circuit • programmable 0 – 5 V, pulse min. 50 mV, steps of 1 mV • 1/10 attenuation: 5 mV 0.5 V, steps of 100 µV • charge injection ~20 fF (0.1 fC 10 fC) • chip configuration done via USB card • record injected signal and discriminated pixel output with oscilloscope • LeCroyWavePro 7100A oscilloscope (20 GS/s for 2 channels, 1 GHz analogue bandwidth)

4. Measurement setup (3)

5. Measurement setup (3) 0.035 V (0.7 fC) threshold Tin

6. Measurement setup (3) 0 V threshold T1 T2

7. Injected pulse signals • nominal pulse amplitudes from 0.06 V to 0.5 V (correspond to 1.2 fC and 10.0 fC resp.) • note: 1/10 attenuation • threshold set to 0.035 V (0.7 fC)

8. Discriminated output signals

9. Injection time measurement (1) • least square method applied to: • Method 1: 3 samples above and below threshold • Method 2: 40 samples on the rising slopes at fixed position (11-13 ns)

10. Injection time measurement (2) • least square method applied to: • Method 1: 3 samples above and below threshold • Method 2: 40 samples on the rising slopes at fixed position (11-13 ns) Tin

11. Discr. times measurement • least square method applied to: • Method 1: 3 samples above and below threshold (0 V) T1 T2

12. Method 2 for Tin Measurement

13. T1 distribution

14. T2 distribution

15. Tin distribution

16. (T1 – Tin) mean value distribution

17. (T2 – Tin) mean value distribution

18. (T1 – Tin) rms distribution

19. (T2 – Tin) rms distribution

20. (T2 – T1) mean value distribution

21. Method 2 Vs Method 1 for Tin Measurement

22. T1 jitter

23. T2 jitter

24. Correction of Injection Baseline Variation

25. Injection baseline variation

26. T1 jitter • variation of 0.035 V (0.7 fC) threshold taking into account (trace by trace) baseline variation • lower T1 jitter

27. Correction of Injection Pulse Height Variation

28. Inject. pulse height variation (1)

29. Inject. pulse height variation (2)

30. Inject. pulse height variation (3)

31. T1 jitter • selection of injected pulse height within ±0.1 mV of local mean value (±0.002 fC) • comparable T1 jitter (lower jitter for first bin only)

32. Time Over Threshold Correction

33. ToT Correction (1) • build Look-Up Table to correct T1 as a function of the signal Time Over Threshold, i.e. (T2 – T1)

34. ToT Correction (2) • from ToT plot fit, extract input charge values using 50 ps wide time intervals (from 10 ns to 20 ns)

35. ToT Correction (3) • from (T1 – Tin) plot fit, compute the time correction to be applied to T1 • then build complete LUT to be used in reconstruction program

36. Results (1) • T1 – Tin distribution becomes flat • error bar = jitter • small shift around ~6 fC due to change in measurement conditions

37. Results (2) • T1 jitter consistent with value before correction • problem with the same 2 points around 6 fC

38. Results (3) • problem with 2 points around ~6 fC due to events “leak” from one bin to the next one around the “threshold” for anomalous Tin behavior

39. Results (3) • problem with 2 points around ~6 fC due to events “leak” from one bin to the next one around the “threshold” for anomalous Tin behavior

40. Results (3) • problem with 2 points around 6 fC due to events “leak” from one bin to the next one around the “threshold” for anomalous Tin behavior

41. Geant 4 Simulation

42. Energy release GTK per hit • mean energy: 72.4 keV (~20.1 ke-h~3.2 fC) • most probable energy: 53.7 keV (~14.9 ke-h~2.4 fC) • FWHM: ~25 keV (~6.9 ke-h ~1.1 fC) • minimum energy: ~29 keV (~8.1 ke-h~1.3 fC)

43. Charge-weighted T1 jitter value • taking into account the energy distribution of particle hits in the Gigatracker, one can extract a weighted average value for the jitter on T1

44. Final Results and TO DO List • Charge weighted average result: (70 ± 5) ps • CAVEAT measurements done with: • 20 pF pixel input capacitance • 2.5 ns pulse injection rise time • 35 °C ambient temperature • Comparison with simulation: • simulations from J. Kaplon show 30-40 psrms (160 pspk-pk) for a 3.0 fC signal • measurements show ~70 psrms for 3.0 fC • TO DO list: • identify other (possible) systematic effects in the measured quantities and correct for them • analyze data samples at different temperatures (-5, 5, 15, 25 °C)

45. Conclusions • T1 jitter lower than ~140 ps for charge injection greater than 1.0 fC • Charge weighted jitter is ~70 ps • ToT correction technique works well: LUT has been produced for fast offline correction • Developed software tool for the analysis of measurement data which fits into the existing testing setup

46. SPARES

48. Energy release GTK per hit (2) • mean energy: 72.4 keV (~20.1 ke-h~3.2 fC) • most probable energy: 53.7 keV (~14.9 ke-h~2.4 fC) • FWHM: ~25 keV (~6.9 ke-h ~1.1 fC) • minimum energy: ~29 keV (~8.1 ke-h~1.3 fC)